Hypercalcemic Encephalopathy in the Course of Hyperthyroidism

In this narrative review we focus on acute symptomatic seizures occurring in subjects with electrolyte disturbances. Quite surprisingly, despite its clinical relevance, this issue has received very little attention in the scientific literature. Electrolyte abnormalities are commonly encountered in clinical daily practice, and their diagnosis relies on routine laboratory findings. Acute and severe electrolyte imbalances can manifest with seizures, which may be the sole presenting symptom. Seizures are more frequently observed in patients with sodium disorders (especially hyponatremia), hypocalcemia, and hypomagnesemia. They do not entail a diagnosis of epilepsy, but are classified as acute symptomatic seizures. EEG has little specificity in differentiating between various electrolyte disturbances. The prominent EEG feature is slowing of the normal background activity, although other EEG findings, including various epileptiform abnormalities may occur. An accurate and prompt diagnosis should be established for a successful management of seizures, as rapid identification and correction of the underlying electrolyte disturbance (rather than an antiepileptic treatment) are of crucial importance in the control of seizures and prevention of permanent brain damage.

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“…However, hypercalcemia-induced hypertensive encephalopathy and vasoconstriction have been hypothesized to be responsible for seizures. 3 14 74 …”

Section: Hypercalcemiamentioning

confidence: 99%

Acute Symptomatic Seizures Caused by Electrolyte Disturbances

2016

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“…In hypercalcemia, EEG changes (fast activity and burst of delta and theta slowing) appear when calcium levels reach ∼13 mg/dl. As calcium level increases, increased background slowing (largely frontal), paroxysmal theta/delta bursts, and TWs may appear (Juvarra et al, 1985; Kaplan, 2004a). Diffuse and more occipital spike–slow‐wave complexes may be found, suggesting a calcium‐mediated vasospastic effect in the posterior cerebral circulation, also noted with very high calcium levels (Kaplan, 1998).…”

Section: The Eeg In Electrolyte Disturbancesmentioning

confidence: 99%

Electrolytes Disturbances and Seizures

et al. 2006

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“…A course similar to our case report was described in a patient with mild hypercalcemia and hyperthyroidism. 14 It has been proposed that encephalopathy in hypercalcemia, unlike in other metabolic disorders, develops only after a chronic elevation of serum calcium levels, 15 whereas in infusion-accentuated hypercalcemia there are no marked changes in the EEG. 16 Unfortunately, we do not know how long hypercalcemia had been present in our patient before admission to our department.…”

Section: Discussionmentioning

confidence: 99%

“…There were only 2 patients with myoclonic jerks in the case series of Cornette and Grisar, 7 and none in the cases described by others. 1,6,10,13,14,16,19,20…”

Section: Discussionmentioning

confidence: 99%

Creutzfeldt-Jakob–Like Syndrome due to Hypercalcemic Encephalopathy

2014

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Hypercalcemia can cause a subacute syndrome of progressive dementia and marked changes in the electroencephalogram (EEG). We report a case of iatrogenic hypercalcemia with a close correlation between the clinical course and the EEG changes. A 73-year-old woman presented with a subacute syndrome of progressive dementia and bursts of 1.5 to 2 Hz intermittent rhythmic delta activity superimposed on a low-voltage background activity in the EEG. Clinical and EEG abnormalities rapidly resolved after normalization of serum calcium levels. As part of the diagnostic workup of a subacute progressive dementia, a serum calcium level and an EEG should be obtained to detect a Creutzfeldt-Jakob like syndrome in hypercalcemia. Unlike in Creutzfeldt-Jakob disease, and Creutzfeldt-Jakob-like syndrome induced by lithium intoxication, there are rarely myoclonic jerks and periodic discharges in hypercalcemic encephalopathy.

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Hypercalcemic Encephalopathy in the Course of Hyperthyroidism

Cited by 9 publications

References 11 publications

Acute Symptomatic Seizures Caused by Electrolyte Disturbances

Acute Symptomatic Seizures Caused by Electrolyte Disturbances

Electrolytes Disturbances and Seizures

Creutzfeldt-Jakob–Like Syndrome due to Hypercalcemic Encephalopathy

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